Refrigerators for commercial use have recently been provided with an inverter-driven compressor in which speed control is possible (for example, see Patent Document 1).
There are various advantages to providing an inverter-driven compressor, and an example thereof is that higher efficiency can be achieved when performing a control-cooling operation. The reason is that, in the case of performing a control-cooling operation that maintains the inside of a cabinet at a set target temperature, when the internal temperature approaches the target temperature, control is performed to gradually reduce the speed (rotational speed) of the inverter-driven compressor in response thereto. By adopting this control method, a period of time in which the compressor is continuously in an on state is extremely long. In other words, the number of times of switching between an on state and an off state is significantly decreased, and thus higher efficiency and energy savings can be achieved.